Network Layer (OSI)
The Network layer is the third layer of the OSI model. Technologies at this layer are focused on getting traffic from one network to another. This may be across multiple networks.
The Internet Protocol (IP) is the most common protocol at layer 3. Subnets represent layer-3 networks.
Routers are a common piece of equipment at layer-3. They are responsible for passing traffic from one network to the next. They also find the best path to a destination network.
The Internet Protocol breaks information into manageable pieces of information called packets. The receiving device reassembles packets into the original information.